1. Field of the Invention
This invention relates generally to the field of electrosurgery and more particularly, to radio frequency apparatus and to wands bearing electrodes for delivering such radio frequency therapy.
2. Background of the Invention
Instability of joints is a significant cause of disability or limitation in patients who are active in their daily activities, work or sports. The joints provide varying degrees of freedom of movement. The knee, for instance, is a joint with essentially one degree of freedom, acting primarily as a hinge. A second, subordinate degree of freedom, rotation around the long axis of the leg, only occurs when the knee is flexed. Thus, the knee provides great stability in complete extension when the knee bears the weight of the body, and great mobility when a certain measure of flexion is achieved, as in walking or running. Reduced interlocking of articulating surfaces provide stability coupled with mobility, but render the knee liable to sprains and dislocations. The shoulder is also vulnerable. It is an open ball and socket joint exhibiting three axes and three degrees of freedom, thereby providing great freedom of movement at the expense of stability. The possibility of injury to the shoulder joint is, therefore, quite high.
Joints such as the knee and shoulder are comprised of articulating surfaces at the ends of adjoining bones and coverings of hyaline cartilage surrounded by a soft tissue joint capsule which maintains constant contact with the cartilage surfaces. The joint capsule also maintains the synovial fluid within the joint. Synovial fluid lubricates the joint surfaces. Around the joint capsule, ligaments reinforce and hold the joints together while controlling or restricting certain movements of the joint. Ligaments, joint capsule, and connective tissue are comprised mainly of collagen.
When a joint becomes unstable, its soft tissue or bony structure allows for excessive motion of the joints surfaces relative to each other, and in a direction not normally permitted by the ligaments or capsule. One contributing cause of instability is lengthening of the cartilage comprising ligaments, joint capsule, and connective tissue which surround the joint. The more motion a joint normally provides, the looser the soft tissue and cartilage surrounding the joint. This makes some joints inherently more unstable than others. The shoulder, for example, is a loose joint with great mobility. It is consequently prone to instability.
Instability of the shoulder and other joints can occur congenitally, developmentally or traumatically and often becomes recurrent, requiring surgical repair. Surgical repair often involves tightening the surrounding tissues which have become too loose to constrain the motion of the joint. These procedures have been performed through open surgical techniques, often requiring hospitalization and prolonged rehabilitation.
More recently, endoscopic (arthoscopic) techniques have been used for achieving these same goals. Performed through a small incision, endoscopic surgery can often be performed on an outpatient basis, and recovery is often faster after the operation. It is difficult, however, to reach and tighten a tissue arthoscopically because of the difficulty in gaining access to the tissue and of controlling the degree of tightening.
A recognized property of collagen connective tissue is hydrothermal shrinkage of collagen fibers when heated. Collagen comprises fibrous crosslinked molecules. At elevated temperature, the cross links appear to be broken and the collagen fibers collapse into a more tangled configuration, with about one third of their original length. At the same time, the cross-sectional dimensions of the fibers increase greatly, but without a significant loss of strength. These characteristics of collagen connective tissue have been utilized in arthoscopic surgery to tighten the supporting structures surrounding a joint. Radio frequency radiation has been used to produce a controlled application of heat, causing the affected tissue to shrink in the direction of its fibrous structure. Commercial devices are available, for example, from Mitek Products and from ArthroCare Corporation. They have also been described in patent literature, for example, U.S. Pat. No. 5,514,130 to Baker and U.S. Pat. No. 5,681,282 to Eggers et al.
Radiant energy is usually applied arthoscopically through an electrode or another energy emitting structure carried on the end of a wand. To accommodate the diverse geometries of the various joints, wands of different configurations have been proposed. In addition to straight wands, wands having curved tips or bendable tips are known. Remotely deflectable tips for wands have been proposed. See, for example, Baker U.S. Pat. No. 5,514,130. There remain needs, however, for further development in the controlled application of heat producing energy in arthoscopic surgery.
It is an object, therefore, of our invention, to provide an arthoscopic surgical apparatus for application of heat producing energy at selected locations within the joint of the patient.
It is also an option of an object of our invention to provide an electrode bearing wand with an articulating distal tip.
A further object of our invention is to provide an electrode bearing wand with articulating tip which is self-locking in any selected articulating configuration.
Another object of our invention is to provide an electrode bearing wand with an articulating tip which can resist significant forces applied at the tip by pushing against tissue or bone of a patient""s body.
Another object of our invention is to provide a wand with articulating tip which is relatively structurally rigid in any selected configuration.
We have invented a heat-producing medical apparatus having an application wand which is articulating and self-locking in a selected configuration. Preferably, the apparatus applies radio frequency radiation to contract collagen within a joint of a patient. The wand has a handle having a cylindrical chamber containing a thumb wheel apparatus. A threaded bore extends coaxially through the thumb wheel. A threaded tube received in the threaded bore translates a wire forward and backward to the distal end of the wand. The wire passes through a guide tube on the outer surface of the wand or through a lumen within the wand to the distal end of the wand. At the distal end of the wand the wire passes over a bendable section in the wand. Pushing or pulling the wire bends the distal tip through a range of angles on both sides of a neutral linear position. The distal tip remains self-locked in a selected position when the thumb screw is not turned.